Many individuals, and in particular many athletes, possess serious podiatric conditions and thus require the manufacture of prescription orthotics. But many of the problems commonly encountered stem from inadequate conformance, support and stability. Here, the midsole or insole of the shoe often prove inadequate. Every individual has a different set of feet. The problem to be solved: How to accomodate individual differences and thus provide superior conformance, stability and comfort in a mass produced article of footwear?
There have been a number of attempted solutions to this problem which have enjoyed varied success. Obvious merits aside, some of the deficiencies of the prior art will be briefly addressed.
As mentioned above, orthotics are sometimes required to correct serious podiatric conditions. For some individuals there is no practical alternative. But orthotics take considerable time for a specialist to fabricate and are thus relatively expensive. They are neither a viable practical alternative, nor truly necessary for the general public. Moreover, many orthotic devices are rigid and do not permit adequate flexion of the arch(es). Orthotics are seldom fixed within the shoe in a manner that would prevent their slipping about. Such movement produces discomfort for the wearer and partially nullifies the corrective value of the orthotic. Furthermore, the insertion of an orthotic device will often change the conforming properties of the last of the shoe resulting in poor fit and discomfort.
Pre-formed insoles of various kinds accomodate a greater, or lesser number of individuals depending upon the incorporation of characteristic norms in their design. But as every individual has a different set of feet, a pre-formed insole will not accomodate every individual to the same degree.
There have been a number of attempts to introduce deformable, or elastomeric materials into the midsole, or insole of an article of footwear so as to provide a "custom" fit for any given individual. The present invention would fall into this category. Some of the prior art designs have proven inadequate because of improper design, or application. For example, reference is made to foot supports which are made of elastomeric material(s) and which underlie the entire foot (in particular, the area forward of the metatarsals). In the practical application such would induce serious biomechanical complications.
Reference is also made to attempts to introduce such quantity of elastomeric material(s) as to alter the foot's proper conformance with the last of the shoe.
In addition, some inventors have wanted for suitable elastomeric materials that would set to the desired consistency during a convenient time period. Others, possessing such materials, have not adequately dealt with the problem posed by exothermic (heat producing) reactions. Few inventors have made an attempt to accomodate the flexion of the arch(es), and many have suggested means that have proven largely impracticable. And few inventors have thought to provide a means of construction and adhesion that would permit easy removal and replacement of an accomodative device.
There have also been a number of ideas as to how to introduce and contain elastomeric material(s) within an article of footwear. Many have thought to inject the material by various means, whereas others have thought to otherwise contain, or enclose the same. The procedures and methods to be associated with these attempts have for the most part been relatively complex, time consuming, expensive, or otherwise not amenable to mass production and use by the general public. In fact, it is perceived that these shortcomings are responsible for the failure of the leading manufacturers of footwear to incorporate a midsole construction, or insert employing elastomeric material(s).